1. Field of the Invention
The present invention relates to a shifting device for rolling stock placed on a roller conveyor. The shifting device includes a pair of linear shifting members which can be moved toward each other and away from each other transversely of the conveying direction of the roller conveyor and above the conveying plane of the roller conveyor, wherein the linear shifting members are each arranged on guide crossheads which are supported on rollers and are driven by drive devices arranged stationary outside of the roller conveyor so as to move the guide crossheads between and parallel to the rollers of the roller conveyor.
2. Description of the Related Art
In a shifting device of the above-described type disclosed in German Patent 961,797, the linear sliding members are provided with eccentric bushings which are placed in the linear sliding members, wherein the eccentric bushings are supported by vertical bolts which are rigidly connected to the guide crossheads. The guide crossheads are located underneath the rollers of the roller conveyor on a roll of support rollers which are supported in stationary crossbeams of the support frame of the roller conveyor. The guide crossheads are driven in pairs by longitudinal toothings of toothed gear motors arranged outside of the roller conveyor.
This known shifting device has the disadvantage that the structural weight of the guide crossheads is relatively high because of the long force transmission distances and require additional structural measures for the lateral guidance thereof. In addition, the drive units and the sliding distances of the guide crossheads with the lateral guide means thereof require a large amount of space outside of the roller conveyor and, moreover, the arrangement of the stationary crossbeams with the more or less high number of rollers which support the guide crossheads require additional space underneath the roller conveyor and the corresponding structural features. Even this shifting device is very complicated, the accuracy of the centering movements for the rolling stock which can be achieved with this shifting device is frequently not satisfactory.